US 12,109,793 B2
Composite skins having variable hole sizes and shapes formed using photomachining
Brian Kenneth Holland, Mason, MI (US); Bruce L Morin, Longmeadow, MA (US); Michael Joseph Murphy, Windsor, CT (US); and Steven H. Zysman, Amston, CT (US)
Assigned to RTX CORPORATION, Farmington, CT (US)
Filed by UNITED TECHNOLOGIES CORPORATION, Farmington, CT (US)
Filed on Nov. 21, 2019, as Appl. No. 16/690,519.
Prior Publication US 2021/0158792 A1, May 27, 2021
Int. Cl. B32B 38/10 (2006.01); B24C 1/04 (2006.01); B32B 3/12 (2006.01); B32B 3/26 (2006.01); B32B 5/02 (2006.01); B32B 37/14 (2006.01); B32B 37/18 (2006.01); G10K 11/168 (2006.01)
CPC B32B 38/10 (2013.01) [B24C 1/045 (2013.01); B32B 3/12 (2013.01); B32B 3/266 (2013.01); B32B 5/02 (2013.01); B32B 37/146 (2013.01); B32B 37/18 (2013.01); G10K 11/168 (2013.01); B32B 2262/101 (2013.01); B32B 2262/106 (2013.01); B32B 2305/02 (2013.01); B32B 2315/00 (2013.01); B32B 2419/04 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method of fabricating a face skin for an acoustic panel of a nacelle configured to surround a central longitudinal axis of a gas turbine engine, the method comprising:
locating a masking film over a first surface of a sheet configured to form the face skin for the acoustic panel of the nacelle and thus, configured to surround the central longitudinal axis of the gas turbine engine, the masking film defining a plurality of openings;
forming a plurality of slots in the sheet using abrasive blasting, wherein each slot of the plurality of slots has a length dimension and a width dimension, the length dimension being greater than the width dimension, and wherein each slot is oriented such that the length dimension is substantially perpendicular to an expected direction of airflow through the gas turbine engine and over the slot, the plurality of slots configured to be oriented at an angle relative to the central longitudinal axis of the gas turbine engine, where the central longitudinal axis is different from the expected direction of airflow through the gas turbine engine, wherein the angle is defined by a centerline of each slot of the plurality of slots and the central longitudinal axis, wherein a first end of a first semi-circular wall of at least one first slot in the plurality of slots through the face skin is at least one of axially offset or circumferentially offset from a second end of a second semi-circular wall of the at least one first slot though the face skin based upon a degree of a first angle, wherein a first end of a first semi-circular wall of at least one second slot in the plurality of slots through the face skin is at least one of axially offset or circumferentially offset from a second end of a second semi-circular wall of the at least one second slot though the face skin based upon a degree of a second angle, wherein the first angle is different from the second angle, wherein the plurality of slots in the sheet comprises forming at least three regions with a first region of the sheet having a first percentage of open area and a first number of slots that is greater than a second percentage of open area and a second number of slots in a second region of the sheet and greater than a third percentage of open area and a third number of slots in a third region of the sheet, wherein the second percentage of open area and the second number of slots in the second region of the sheet is greater than the third percentage of open area and the third number of slots in the third region of the sheet, and wherein a percentage of open area and a number of slots in each of the first region, the second region and the third region is selected based on an expected velocity of the airglow over a respective region and acoustic characteristics experienced in the respective region; and wherein the first number of slots is offset from the second number of slots; and
removing the masking film.